/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Collections.Specialized;
using System.Configuration;
using Spring.Util;

namespace Spring.Objects.Factory.Config;

/// <summary>
/// Implementation of <see cref="IVariableSource"/> that
/// resolves variable name against name-value sections in
/// the standard .NET configuration file.
/// </summary>
/// <author>Aleksandar Seovic</author>
[Serializable]
public class ConfigSectionVariableSource : IVariableSource
{
    private string[] sectionNames;
    protected NameValueCollection variables;
    private readonly object objectMonitor = new object();

    /// <summary>
    /// Initializes a new instance of <see cref="ConfigSectionVariableSource"/>
    /// </summary>
    public ConfigSectionVariableSource()
    {
    }

    /// <summary>
    /// Initializes a new instance of <see cref="ConfigSectionVariableSource"/> from the given <paramref name="sectionName"/>
    /// </summary>
    public ConfigSectionVariableSource(string sectionName)
    {
        this.SectionName = sectionName;
    }

    /// <summary>
    /// Initializes a new instance of <see cref="ConfigSectionVariableSource"/> from the given <paramref name="sectionNames"/>
    /// </summary>
    public ConfigSectionVariableSource(string[] sectionNames)
    {
        this.SectionNames = sectionNames;
    }

    /// <summary>
    /// Gets or sets a list of section names variables should be loaded from.
    /// </summary>
    /// <remarks>
    /// All sections specified need to be handled by the <see cref="NameValueSectionHandler"/>
    /// in order to be processed successfully.
    /// </remarks>
    /// <value>
    /// A list of section names variables should be loaded from.
    /// </value>
    public string[] SectionNames
    {
        get { return sectionNames; }
        set { sectionNames = value; }
    }

    /// <summary>
    /// Convinience property. Gets or sets a single section
    /// to read properties from.
    /// </summary>
    /// <remarks>
    /// The section specified needs to be handled by the <see cref="NameValueSectionHandler"/>
    /// in order to be processed successfully.
    /// </remarks>
    /// <value>
    /// A section to read properties from.
    /// </value>
    public string SectionName
    {
        set { sectionNames = new string[] { value }; }
    }

    /// <summary>
    /// Before requesting a variable resolution, a client should
    /// ask, whether the source can resolve a particular variable name.
    /// </summary>
    /// <param name="name">the name of the variable to resolve</param>
    /// <returns><c>true</c> if the variable can be resolved, <c>false</c> otherwise</returns>
    public bool CanResolveVariable(string name)
    {
        lock (objectMonitor)
        {
            if (variables == null)
            {
                variables = new NameValueCollection();
                InitVariables();
            }

            return CollectionUtils.Contains(variables.AllKeys, name);
        }
    }

    /// <summary>
    /// Resolves variable value for the specified variable name.
    /// </summary>
    /// <param name="name">
    /// The name of the variable to resolve.
    /// </param>
    /// <returns>
    /// The variable value if able to resolve, <c>null</c> otherwise.
    /// </returns>
    public string ResolveVariable(string name)
    {
        lock (objectMonitor)
        {
            if (variables == null)
            {
                variables = new NameValueCollection();
                InitVariables();
            }

            return variables.Get(name);
        }
    }

    /// <summary>
    /// Initializes properties based on the specified
    /// property file locations.
    /// </summary>
    protected virtual void InitVariables()
    {
        foreach (string sectionName in sectionNames)
        {
            object section = ConfigurationUtils.GetSection(sectionName);
            if (section is NameValueCollection)
            {
                variables.Add((NameValueCollection) section);
            }
            else if (section is ClientSettingsSection)
            {
                ClientSettingsSection clientSettingsSection = (ClientSettingsSection) section;
                foreach (SettingElement setting in clientSettingsSection.Settings)
                {
                    variables.Add(setting.Name, setting.Value.ValueXml.InnerText);
                }
            }
            else
            {
                throw new ArgumentException("Section [" + sectionName +
                                            "] is not handled by the NameValueSectionHandler.");
            }
        }
    }
}
